Superconductive rotor, superconductive rotating machine and superconductive rotating-machine system

Abstract

The main problem to be solved by the invention is to provide a superconductive rotor, a superconductive rotating machine and a superconductive rotating-machine system which are capable of inductive and synchronous rotation while employing the induction machine configuration and also offer satisfactory heat dissipation performance, stability under an excessive load, and easy magnetic flux trap for synchronous rotation. To solve the problem, the invention provides a superconductive rotor, as shown in FIG. 1 , including a superconductive squirrel-cage winding formed by superconductive wires having a plurality of superconductive wires covered with a highly conductive metal; a normally conductive squirrel-cage winding formed by a normally conductive material; a cylindrical rotor core having a plurality of slots for accommodating the rotor bars of both of the squirrel-cage windings; and a rotor shaft coaxially provided to the rotor core, wherein, when the superconductive squirrel-cage winding is in a non-superconductive state, rotations are mainly made by an induced torque generated on the normally conductive squirrel-cage winding due to a rotating magnetic field and, when the superconductive squirrel-cage winding is in a superconductive state, rotations are mainly made by a synchronous torque generated by the superconductive squirrel-cage winding trapping magnetic flux of the rotating magnetic field.

1. A superconductive rotor disposed to be rotated in a stator for generating a rotating magnetic field, comprising:
 a superconductive squirrel-cage winding formed by rotor bars and end rings, the rotor bars including one or more superconductive wires having a plurality of superconductive wires covered with a highly conductive metal; 
 a normally conductive squirrel-cage winding formed by rotor bars and end rings, which are made of a normally conductive material; 
 a cylindrical rotor core having a plurality of slots for accommodating the rotor bars of both of the squirrel-cage windings; and 
 a rotor shaft coaxially provided to the rotor core, wherein, 
 when the superconductive squirrel-cage winding is in a non-superconductive state, rotations are mainly made by an induced torque generated on the normally conductive squirrel-cage winding due to a rotating magnetic field and, when the superconductive squirrel-cage winding is in a superconductive state, rotations are mainly made by a synchronous torque generated by the superconductive squirrel-cage winding trapping magnetic flux of the rotating magnetic field. 
 
     
     
       2. The superconductive rotor according to  claim 1 , wherein,
 the superconductive wire is made of a low-temperature superconductor based on a metal as typified by NbTi or Nb 3 Sn, a high-temperature superconductor based on an oxide as typified by yttrium or bismuth, or a magnesium diboride superconductor, and 
 the highly conductive metal is silver, copper, gold, aluminum, or an alloy thereof. 
 
     
     
       3. The superconductive rotor according to  claim 1 , wherein the normally conductive squirrel-cage winding is formed by increasing the thickness of the highly conductive metal in the superconductive squirrel-cage winding to a predetermined value or more, and is integrated with the superconductive squirrel-cage winding. 
     
     
       4. The superconductive rotor according to  claim 1 , wherein the superconductive squirrel-cage winding and the normally conductive squirrel-cage winding are provided independently of each other, and the superconductive squirrel-cage winding has a larger cage than that of the normally conductive squirrel-cage winding so that the rotor bars thereof are positioned outside the rotor bars of the normally conductive squirrel-cage winding. 
     
     
       5. The superconductive rotor according to  claim 1 , wherein the superconductive squirrel-cage winding and the normally conductive squirrel-cage winding are provided independently of each other, and the normally conductive squirrel-cage winding has a larger cage than that of the superconductive squirrel-cage winding so that the rotor bars thereof are positioned outside the rotor bars of the superconductive squirrel-cage winding. 
     
     
       6. The superconductive rotor according to  claim 1 , wherein the number of rotor bars of the superconductive squirrel-cage winding and the number of rotor bars of the normally conductive squirrel-cage winding are equal to the number of the slots in the rotor core, and each of the slots accommodates one rotor bar of each of the superconductive squirrel-cage winding and the normally conductive squirrel-cage winding. 
     
     
       7. A superconductive rotating machine having a superconductive rotor of  claim 1  disposed in a stator including a stator winding for generating a rotating magnetic field. 
     
     
       8. The superconductive rotating machine according to  claim 7 , wherein the stator winding is made of a superconductive material, and the superconductive material has a critical temperature higher than or equal to a critical temperature of the superconductive wires included in the superconductive squirrel-cage winding. 
     
     
       9. A superconductive rotating-machine system comprising:
 a superconductive rotating machine of  claim 7 ; 
 a cooling device capable of cooling the superconductive rotating machine to a superconductive state; and 
 a control device for controlling the superconductive rotating machine, wherein, 
 the control device has a first control pattern to be used when the superconductive rotating machine is mainly rotated by the induced torque and a second control pattern to be used when the superconductive rotating machine is mainly rotated by the synchronous torque, such that the superconductive rotating machine is controlled using the second control pattern when a value of current flowing through the stator winding falls due to the superconductive squirrel-cage winding being brought into the superconductive state, and when otherwise, the superconductive rotating machine is controlled using the first control pattern. 
 
     
     
       10. The superconductive rotating-machine system according to  claim 9 , wherein, when the superconductive squirrel-cage winding is in the superconductive state without trapping magnetic flux of the rotating magnetic field at start-up, the control device changes a voltage applied to the stator winding and/or a frequency of the applied voltage such that current flowing through the superconductive squirrel-cage winding exceeds a critical level, thereby bringing the superconductive squirrel-cage winding into a state of magnetic flux flow, allowing the magnetic flux of the rotating magnetic field to link the superconductive squirrel-cage winding. 
     
     
       11. The superconductive rotor according to  claim 2 , wherein the normally conductive squirrel-cage winding is formed by increasing the thickness of the highly conductive metal in the superconductive squirrel-cage winding to a predetermined value or more, and is integrated with the superconductive squirrel-cage winding. 
     
     
       12. The superconductive rotor according to  claim 2 , wherein the superconductive squirrel-cage winding and the normally conductive squirrel-cage winding are provided independently of each other, and the superconductive squirrel-cage winding has a larger cage than that of the normally conductive squirrel-cage winding so that the rotor bars thereof are positioned outside the rotor bars of the normally conductive squirrel-cage winding. 
     
     
       13. The superconductive rotor according to  claim 2 , wherein the superconductive squirrel-cage winding and the normally conductive squirrel-cage winding are provided independently of each other, and the normally conductive squirrel-cage winding has a larger cage than that of the superconductive squirrel-cage winding so that the rotor bars thereof are positioned outside the rotor bars of the superconductive squirrel-cage winding. 
     
     
       14. The superconductive rotor according to  claim 2 , wherein the number of rotor bars of the superconductive squirrel-cage winding and the number of rotor bars of the normally conductive squirrel-cage winding are equal to the number of the slots in the rotor core, and each of the slots accommodates one rotor bar of each of the superconductive squirrel-cage winding and the normally conductive squirrel-cage winding. 
     
     
       15. The superconductive rotor according to  claim 3 , wherein the number of rotor bars of the superconductive squirrel-cage winding and the number of rotor bars of the normally conductive squirrel-cage winding are equal to the number of the slots in the rotor core, and each of the slots accommodates one rotor bar of each of the superconductive squirrel-cage winding and the normally conductive squirrel-cage winding. 
     
     
       16. The superconductive rotor according to  claim 4 , wherein the number of rotor bars of the superconductive squirrel-cage winding and the number of rotor bars of the normally conductive squirrel-cage winding are equal to the number of the slots in the rotor core, and each of the slots accommodates one rotor bar of each of the superconductive squirrel-cage winding and the normally conductive squirrel-cage winding. 
     
     
       17. The superconductive rotor according to  claim 5 , wherein the number of rotor bars of the superconductive squirrel-cage winding and the number of rotor bars of the normally conductive squirrel-cage winding are equal to the number of the slots in the rotor core, and each of the slots accommodates one rotor bar of each of the superconductive squirrel-cage winding and the normally conductive squirrel-cage winding. 
     
     
       18. A superconductive rotating machine having a superconductive rotor of claim disposed in a stator including a stator winding for generating a rotating magnetic field. 
     
     
       19. A superconductive rotating machine having a superconductive rotor of  claim 3  disposed in a stator including a stator winding for generating a rotating magnetic field. 
     
     
       20. A superconductive rotating machine having a superconductive rotor of  claim 4  disposed in a stator including a stator winding for generating a rotating magnetic field.